Since the early 21st century, China has broadened its ambition to control the South China Sea to the entire sea area. They not only made statements and took actions to exercise sovereignty over the seas of the Paracel and Spratly Islands, Scarborough or Luconia Shoals but also claimed overlapping sovereignty and dispatched fishing boats backed and protected by Chinese maritime surveillance, coast guard, and navy vessels to the area of Indonesia's Natuna in the southern South China Sea. This directly impacts Indonesia's national sovereignty and interests, forces the country to take a number of measures and actions on different fields to curb China's ambition.

In terms of foreign affairs, Indonesia implemented an "organizational balance" solution by assigning various domestic and overseas agencies to counter and prevent China’s activities violating its sovereignty, in combination with "risk protection" measure connecting regional countries and major powers to address threats as well as emergencies. On regional and international fora, Indonesia firmly rejects China’s statement on the "Nine-dash line" and disapproved Beijing's assertion that "China and Indonesia have overlapping claims on maritime rights and interests in the Natuna Islands". Indonesian Foreign Minister Retno Marsudi emphasized: "We never recognize the 'Nine-dash line' and he said that Indonesian diplomatic agencies need to send signals on their determination of sovereignty and territorial integrity protection and to ensure that this message is not misinterpreted by anyone because Jakarta has stated it is not to participate in the disputes in the South China Sea. On August 16, 2016, after an inspection trip to the Natuna Islands, Indonesian President pledged to protect every inch of land and territorial sea of the country, to prevent illegal encroachment of Chinese fishing boats into Natuna's exclusive economic zone. In the event of the Arbitral tribunal established under Appendix VII of the 1982 UNCLOS on the Philippines vs. China case regarding the South China Sea, President Joko Widodo said Indonesia would actively participate in the dispute resolution between parties through peaceful negotiations, opposing the use of force.

In its relations with China, the Indonesian government is determined to persistently and actively pursue a moderate policy to deal with related matters. Indonesia still hopes China will keep their commitment to Jakarta from the 1990s, saying that "there is no dispute over ownership of the Natuna Islands because the islands belong to Indonesia". Indonesia's Coordinating Minister for Maritime Affairs Luhut Pandjaitan affirmed: "We are still friendly with China and other regional countries, but we must protect ourselves".

In the incident of June 17, 2016 when Indonesian Navy seized Chinese fishing boats and fishermen in Natuna waters, Indonesian Ministry of Foreign Affairs summoned the Chinese Ambassador to explain and clarify the case. In particular, when the Chinese Ministry of Foreign Affairs declared that the exclusive economic zone of the Natuna Islands is China's "traditional fishing ground" and the two sides have "overlapped interests and maritime rights", Indonesia immediately responded with a diplomatic note of objection. The Indonesian government and authorities also issued a public statement that strongly opposed the militarization and presence of Chinese warships in the southern South China Sea, near the Natuna Islands.

Economically speaking, the Indonesian President proposes a comprehensive economic development strategy for the Natuna Islands focusing on promoting fishing, aquatic exploitation, commercial shipping, tourism development, calling for oil and gas investment, combining economy with national defense and security, etc. According to him, it is now essential to give priority to economic development in the Natuna Islands, not only to ensure national interests but also protect large sea area in the North. Thus, Indonesia will invest, develop an integrate marine and fishery center in the region, and plan to send about 6,000 fishermen to catch and exploit seafood around the Natuna Islands. On the energy issue alone, former Minister of Energy and Mineral Resources Sudirman Said confirmed that 16 oil and gas blocks have been designated in this area, of which 5 are in production and 11 are in the phase of exploration and testing. One of the most potential gas fields in the Natuna Islands located in the East area, is considered the largest gas field in Asia, with total reserve estimated at 46,000 billion m3. Currently, Pertamina oil Corporations (Indonesia), Exxon Mobil (USA), Total (France) and SA PTT Exploration (Thailand) are interested in investment cooperation for oil exploitation.

On the legal aspect, on June 20, 2016, the Indonesian Minister of Foreign Affairs made a two-point argument: (1) Indonesia has a clear and internationally recognized maritime border and its claim over the sovereign rights in the exclusive economic zone of the Natuna Islands is fully based on the provisions of the UNCLOS 1982; (2) Indonesia has no dispute with other countries in the South China Sea because Jakarta does not claim any geographic feature of the South China Sea such as islands, reefs or lagoons which are dispute-causing features. Therefore, there is no overlapping area between Indonesia and China. Minister Marsudi affirmed: "This world is organized based on international law rather than on statements based on history. UNCLOS is the law. History cannot deny the law but the law can deny history.

To provide legal support for the protection of its territorial sovereignty, the Government of Indonesia agreed on naming of unnamed islands, first of all, the ones on the border with Timor Leste, Australia and some small islands in the Natuna Islands. Currently, of a total of more than 17,000 islands, 8,844 islands have been named; among the islands with names, only 922 ones are inhabited. The naming of unnamed islands was determined by Indonesia to reinforce its baselines claim, "to prevent neighboring countries from claiming sovereignty" and to help naval forces protect their national maritime areas more easily.

Besides, Indonesia declares it planned to rename waters around the Natuna Islands to "Natuna Sea", covering the entire maritime area in the South-West of the South China Sea, between the Malay Peninsula, Kalimantan and Sumatra islands. If the "Natuna Sea" is officially recognized by the United Nations, the border will run from the Natuna and Anambas Islands in the north, passes by Karimata and Gaspar Straits to Java Sea in the south, and is bordered in the west by the sea between Bintan Island and Malay Peninsula, connects to Singapore Strait and Malacca Strait. According to the Indonesian Government, the policy of renaming the sea around the Natuna Islands to "Natuna Sea" is to: (1) Assert maritime sovereignty, rejecting the so-called "historic interests" and "Nine-dash line" claim of China; (2) Strengthen control at sea, especially the exclusive economic zone around the Natuna Islands, to deploy oil and gas exploration and exploitation, use and management of the seabed and natural resources; (3) Contribute to increasing transparency of maritime sovereign rights, demonstrating its stance to enforce the law on prohibiting illegal fishing, strengthening effective management of government agencies; (4) Justify the legal basis for announcing the "Regional natural resources and oil and gas exploration map around the Natuna Islands and related areas".

In terms of military, in 2002, Indonesia lost Sipadan and Ligitan islands to Malaysia. This is the reason why Jakarta does not want to "a history repeated" in the Natuna Islands, especially when China always claims "historic sovereignty" over this maritime area. President Joko Widodo affirmed that the Indonesian government is determined to protect the islands at its best, taking strict measures against territorial intruders.

In the immediate, in addition to strengthening patrol forces, sending high capacity law enforcement vessels to protect, resolutely arrest and sink or burn any violating foreign fishing boats, the Indonesian Navy would establish the Satgas 115 - a task force - to combat illegal infringement activities. Coordinating Minister of Maritime Affairs and Fisheries Susi Pudjiastuti stated: "Indonesia will not care about which country the ships or ship owners belong to. If they catch our fish, we will punish them straight away irrespective of bilateral relations in such situation”. In 2017, Indonesia's maritime functional forces seized and burnt many illegal foreign fishing vessels, including three Chinese ones. On June 28, 2017, the Indonesian parliament (DPR) approved the 2017 budget for the Ministry of Defense at USD 8.25 billion, an increase of approximate 10% compared to that of 2016. Part of this budget is used to upgrade the existing air base, to build a new port in the Natuna Islands that will allow various warships and aircrafts. Since 2016, Indonesia has conducted many prolonged, large-scale air, naval and army exercises in the Natuna Islands with the participation of thousands of soldiers, aircraft, warships, anti-ship missiles and special forces.

In the long term, Indonesia would strengthen its defense system in the Natuna Islands in response to China's plan to control the South China Sea. It is expected that in the coming years, Indonesia's Ministry of Defense might build radar stations in the Natuna Islands to control the whole area; deploy four more task forces in several islands with important positions; set up a number of small-scale military bases to form a defense system; build two new air bases in Ranai Island and Anambas Islands, permanently deploy Su-27, Su-30 and F-16 jet fighters; increase warehouse facilities, logistics services; deploy a number of multi-purpose air defense artillery complexes, etc. In addition, to strengthen protection of its sovereignty, Indonesia is also keen to develop its naval forces as well as promote defense cooperation with the United States. The two sides have reached policy consensus that the United States would provide technical assistance on equipment for the Indonesian military to build a supposedly largest radar system in the region, with an expected wide range of covering entire the South China Sea and its vicinity.

It can be said that sovereignty and interests competition between China and Indonesia in the surrounding areas of the Natuna Islands have complicated developments, with a potential of turning into fierce clashes. Although the Indonesian government has issued many new guidelines on improving management capacity, diplomatic, military, economic measures and strengthening legal bases, it is difficult to change China's ambition in the South China Sea in general and the Natuna Islands in particular. Therefore, if Indonesia is to protect its interests at sea, it needs to continue to take strong actions against China’s violating sovereignty acts in the Natuna Islands and raise its voice in support of neighboring countries in solving sovereignty disputes in the South China Sea.